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<title>YV12InterlacedReduceBy2</title>
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<h1>YV12InterlacedReduceBy2</h1>
<h2>Abstract</h2>
<b>author:</b> Tom Barry
<br><b>version:</b>  0.1.0.0
<br><b>download:</b> <a href="http://mywebpages.comcast.net/trbarry/downloads.htm">http://mywebpages.comcast.net/trbarry/downloads.htm</a><br>
<b>category:</b> Resizers
<br><b>requirements:</b> &nbsp;
<ul>
  <li> YV12 Colorspace</li>
  <li>SSEMMX (=ISSE) support</li>
</ul>
<hr>
<h2>Description</h2>
<p><code>YV12InterlacedReduceBy2</code> is a fast Reduce By 2 filter. It works by taking only the
even (starting with 0) pixels from the top field. So it will reduce both the
width and height by a factor of 2. It blends the chroma slightly to avoid YV12
chroma delay. </p>
<p><b>USAGE - To use it just: </b></p>
<p>1) Place the InterlacedReduceBy2.dll in a directory somewhere.<br>
2) In your Avisynth file use commands similar to </p>
<pre>LoadPlugin(&quot;F:\YV12InterlacedReduceBy2\YV12InterlacedReduceBy2.dll&quot;)
AviSource(&quot;D:\wherever\myfile.avi&quot;)
YV12InterlacedReduceBy2()</pre>
<p>Of course replace the file and directory names with your own. There are no
parameters. This is usefull as a very fast downsize that needs no deinterlacing.
</p>
<p><b>USAGE 2 </b></p>
<p>There is a second similar function enclosed in the dll called
YV12InterlacedSelectTopFields(). This will select top fields only and adjust for
chroma delay but leave the width unchanged.</p>
<pre>LoadPlugin(&quot;F:\YV12InterlacedReduceBy2\YV12InterlacedReduceBy2.dll&quot;)
Avisource(&quot;D:\wherever\myfile.avi&quot;)
YV12InterlacedSelectTopFields()</pre>
<p>&nbsp;<kbd>$Date: 2005/10/03 16:31:31 $</kbd></p>
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